<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>标签</title>
</head>
<body>
    <!--
        标签分类
            开始和结束标签
            自闭和标签
    -->
    <h1>一级标题</h1>
    <br/>
    <br/>
    <h2>二级标题</h2>
</body>
</html>